From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752079AbdIEQCm (ORCPT ); Tue, 5 Sep 2017 12:02:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:36849 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751979AbdIEQCj (ORCPT ); Tue, 5 Sep 2017 12:02:39 -0400 Date: Tue, 05 Sep 2017 18:02:36 +0200 Message-ID: From: Takashi Iwai To: Sebastian Andrzej Siewior Cc: Takashi Sakamoto , perex@perex.cz, anna-maria@linutronix.de, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, hch@lst.de, keescook@chromium.org, john.stultz@linaro.org, tglx@linutronix.de Subject: Re: [PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer In-Reply-To: <20170905155351.2xmwyxrirndfwtgo@breakpoint.cc> References: <20170901102537.8066-1-o-takashi@sakamocchi.jp> <19775981-a3f2-5f65-e934-bfe25db62a43@sakamocchi.jp> <20170905155351.2xmwyxrirndfwtgo@breakpoint.cc> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.2 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 05 Sep 2017 17:53:51 +0200, Sebastian Andrzej Siewior wrote: > > From: Thomas Gleixner > > The tasklet is used to defer the execution of snd_pcm_period_elapsed() to > the softirq context. Using the CLOCK_MONOTONIC_SOFT base invokes the timer > callback in softirq context as well which renders the tasklet useless. > > Signed-off-by: Thomas Gleixner > Signed-off-by: Anna-Maria Gleixner > Cc: Jaroslav Kysela > Cc: Takashi Iwai > Cc: Takashi Sakamoto > Cc: alsa-devel@alsa-project.org > [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback > of hrtimer] > Signed-off-by: Takashi Sakamoto > Signed-off-by: Sebastian Andrzej Siewior > --- > On 2017-09-02 10:19:45 [+0900], Takashi Sakamoto wrote: > > Yep. I request the authors to include this > Thank you for providing a fix. > > v1…v2: merged Takashi Sakamoto fixup of the original patch into v2. > > So this patch now is okay? Note that you can try it by yourself easily, as it's a dummy driver that doesn't need anything special. Just run aplay for that device (e.g. aplay -Dplughw:2 for card#2) can reproduce the original problem. > @@ -394,7 +386,12 @@ static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer) > dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer); > if (!atomic_read(&dpcm->running)) > return HRTIMER_NORESTART; > - tasklet_schedule(&dpcm->tasklet); > + > + /* In a case of XRUN, this calls .trigger to stop PCM substream. */ As mentioned, the stop happens not only with XRUN but also in a normal situation by draining. Other than that, looks OK to me (but not tested it). thanks, Takashi > + snd_pcm_period_elapsed(dpcm->substream); > + if (!atomic_read(&dpcm->running)) > + return HRTIMER_NORESTART; > + > hrtimer_forward_now(timer, dpcm->period_time); > return HRTIMER_RESTART; > } > @@ -414,14 +411,14 @@ static int dummy_hrtimer_stop(struct snd_pcm_substream *substream) > struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data; > > atomic_set(&dpcm->running, 0); > - hrtimer_cancel(&dpcm->timer); > + if (!hrtimer_callback_running(&dpcm->timer)) > + hrtimer_cancel(&dpcm->timer); > return 0; > } > > static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm) > { > hrtimer_cancel(&dpcm->timer); > - tasklet_kill(&dpcm->tasklet); > } > > static snd_pcm_uframes_t > @@ -466,12 +463,10 @@ static int dummy_hrtimer_create(struct snd_pcm_substream *substream) > if (!dpcm) > return -ENOMEM; > substream->runtime->private_data = dpcm; > - hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > + hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC_SOFT, HRTIMER_MODE_REL); > dpcm->timer.function = dummy_hrtimer_callback; > dpcm->substream = substream; > atomic_set(&dpcm->running, 0); > - tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed, > - (unsigned long)dpcm); > return 0; > } > > -- > 2.14.1 >